Monday, February 28, 2011

Dahlia Pests: Earwigs Creepy, Greedy

The European earwig, one of several dahlia pestsMaybe earwigs are only a nuisance, the way they come skittering out of the florets of a prized dahlia. But sometimes, these creepy dahlia pests are guilty of damaging your dahlia's foliage as well as chewing the flowers and being an unsightly nuisance.

If your dahlia garden is afflicted with earwigs, they're likely the European earwig Forficula auricularia, flattish black or reddish-brown critters from half an inch to 1 1/4 inches long with a distinctive forceps-like appendage at the base of its abdomen.

Like slugs and snails, earwigs are primarily scavengers, says Judy Sedbrook, a Master Gardener with Colorado State University Cooperative Extension. (Earwigs aren't all bad; Sedbrook notes that they are natural enemies of some dahlia pests like mites and aphids.) And like slugs and snails, earwigs are largely nocturnal and fond of moist habitat. In the daylight, they seek out hiding places, congregating under garden debris (they lay their eggs in the soil in such sheltered places) or taking refuge in the convenient tubelike florets of your dahlia blossoms.

At Lynch Creek Farm, where the gang markets dahlia blooms in summer as well as beautiful dahlia tubers for your home gardens, Andy and Nathanael offer this advice: if you suspect your dahlia flower may harbor an earwig or two, dip it into a bucket of cool water. The bug or bugs will wriggle out immediately, and you can leave them swimming.

Strategies for protecting your garden from dahlia pests like earwigs:

To prevent a mild nuisance from becoming a destructive invasion, Carol Savonen of Oregon State University cites guidelines of the University of California Integrated Pest Management Project for eliminating earwigs and similar dahlia pests:
  • Get rid of earwig habitat, such as boards, debris piles, dirt clods, ivy and weeds.
  • Encourage natural predators such as birds and toads. Maintaining some natural areas can help with this, so long as they don't provide moist refuges for earwigs.
  • Make earwig traps with low-sided tuna or pet-food cans filled with half an inch of vegetable oil; dump oil and earwigs when they fill. Or put out rolled newspapers or sections of hose in the evening; in the morning, shake earwigs out into a bucket of water. Continue trapping until you no longer attract earwigs.

An unsightly nuisance, yes. Destructive of your plants, sometimes. But we have to say this on behalf of earwigs: they don't crawl into your ears and eat your brains. That, at least, is an old wives' tale.

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